You are correct. The Aux inputs go directly to the 328 speaker
amplifier. If you do not have all of the switch positions on the
audio panel filled you can add a PCB mount switch to the audio panel
to switch in your new audio source. This is what I did for my 2m ham
radio that I installed in my Cessna. The only place I have found the
schematic for the audio panel is in the "74 through 76 avionic
installations' manual.

On 14 Apr 2004 20:15:54 -0700, (N7155A) wrote:

Under the supervision of my IA, we installed a vor radio. I connected
the vor audio output to one of the Aud-Audio inputs on the RT328D,
thinking this would supply audio to the intercom (connected to the
RT328 phone output) and the speaker.

The VOR radio output only appears to go to the speaker (via RT328D).
I expected these aux-audio to go to the rt328 phone output, but that
doesn't appear to be the case. I guess I need to get an rt328
instruction manual or schematics to determine the function of the
aux-audio inputs.

Any help would is greatly appreciated.

Mitch